ELI5 how do accounts on steemit work and where's my trusted secure cold storage?

I'm trying to wrap my head around the Steem, the new kid on the blockchain.

1. I have an account on steemit.com, obviously, it's @jpk . Is this an account on a website, steemit.com? Or is this an entity registered in the blockchain and steemit serves as a front end?
2. The account has a randomly generate 'password'? Is this a password, checked against a hash in a database behind steemit.com? Or is it a private key used to sign messages on the blockchain?
3. OK, looks like the master password is a master key. Maybe, this shouldn't be in my (insecure) browser? Can I move my funds to cold storage? Without loosing voting and posting privileges? Yes!
4. So, I understand, due to crazy inflation no one wants to hold Steem. I should hold Steem Power to have voting power and earn internet points (=Steem Power) like crazy. This locks up my 'investment' in the Steem ecosystem.
5. In 2 years or 104 payments, or so they told me, I'll get liquid assets back. But, how the heck, does this actually work? Do I get regularly payments (which have to move away from Steem as soon as possible because crazy inflation)? Do I have to initiate regular payments (and then proceed as above)?
6. And, Steem Dollars? Why, just why? Why do my internet points have a dollar value?

Anyone cares to explain?